If we're to compare the Jackson to the Panther as you seem so apt to do you have to factor in the Jackson's significant range advantage over the Panther (60 vs 50). Combine this with the speed of the Jackson and with proper micro it isn't all that hard to beat Panthers with Jacksons, especially considering the much higher cost of the Panther. This becomes even easier in a proper team game (since as I've already admitted, TDs in general seem to underperform in 1v1s [except the OKW panther] because you're spending so many resources on strict AT capabilities) when you combine the Jackson with the power of Soviet/M20 mines, Mark Target, AT nades, ZiS/USF AT guns etc etc.
Statistically the Jackson is an extremely powerful TD, it only lacks in armor and HP - but it more than makes up for that with the punch it brings to the field - and in practice the Jackson is the most powerful TD in the game (barring Elefant/JT) by a wide margin. The only thing it need fear are AT guns, as it should, because they're the natural and necessary counter to a TD like the Jackson.
Comparing a Jackson capabilities with a Jackson capabilities when supported by XX AI and AT is a flaw. Or you have to compare it with a Panther supported by an equal force.
But the main gap in your expose is that High level players can pretty well handle the all around the Jackson, what is usually called microing your army. For the common players - this is not the same thing, blobbing is more an issue and blobbing + heavy tanks make you feel the Jackson underpowered.
The second point where I would tone down your argument is about the capability of the Jackson.
- Yes it has the best DPS in the game, but only if it pen.
- Yes it has the best offensiveness vet in the game, but only available if it pen
I can have incredible games with the Jackson, if it pen. If it doesn't it is just a rubbish thing incredibly expensive.
I'm agreeing with you, the Jackson doesn't really need a buff. It needs a redesign, being less RNG dependent for pen and vet, something like less dps but more pen at vet0. And probably like for any other tanks and TD in the game, a way to escape if you micro well a close combat.
All other tanks and TD in the game have a escape capability, or a ability like smoke, or a good armor that give you enough time to retreat and secure.